Reset isSaving to false when the record is not dirty.

Since saving is a noop when the record is not dirty, we don't actually call the adapter's saveRecord (or createRecord) method. Because of this, nothing ever resets the isSaving state back to false when it's "done".
Make findQuery use collectionKey
Add assertion to Model#findMany
Merge pull request #42 from darthdeus/find-query-collection-key

Make findQuery use collectionKey
Merge pull request #44 from darthdeus/add-find-many-assertion

Add assertion to Model#findMany
Use Ember.get to get collectionKey and rootKey

This change will allow setting collectionKey and rootKey to a computed
property in a superclass of models, for example:

    App.Model = Ember.Model.extend();

    App.Model.reopenClass({
      collectionKey: function() {
        return this.singularName();
      }.property()
    });

    App.Post = App.Model.extend();
Merge pull request #47 from drogus/more-ember-get

Use Ember.get to get collectionKey and rootKey
Tests fix for 9ec8bab72e

The code in 9ec8bab72e is correct, but tests are not, they were not
actually testing the required part as new tests were using RESTModel
instead of AModel.

In fact, usage of additional model was not necessary, beacsue RESTModel
class is recreated before running each of the tests, which means it can
be safely reopend, thus I returned to using RESTModel in all examples.
Implement callbacks in RESTAdapter

When using RESTAdapter it's convenient to override what happens after
finishing the ajax request (for example: sideload extra data).

This commit adds the following callbacks:

* didFind
* didFindAll
* didFindQuery
* didCreateRecord
* didSaveRecord
* didDeleteRecord
Merge pull request #48 from drogus/adapter-callbacks

Adapter callbacks (`didFind`, `didFindAll` etc)
Don't convert null to object when fetching attr

typeof(null) returns "object" in javascript, which was incorrectly
causing attr to call Ember.create(null)
Ensure that adapter callbacks' context is always adapter
Merge pull request #52 from drogus/dont-convert-null-to-object

Don't convert null to object when fetching attr
Merge pull request #51 from drogus/adapter-callbacks-context

Ensure that adapter callbacks' context is always adapter
Merge pull request #54 from eventualbuddha/reset-is-saving-on-non-dirty-save

Reset isSaving to false when the record is not dirty.